The invention relates to an electro-magnetically controlled switch apparatus having in a case an electro-magnet adapted to move an armature subjected to the force of a return spring developing an initial force, a contact holder associated with the armature and presenting side-by-side a plurality of pairs of housings each comprising a lower housing close to the armature and an upper housing placed above, a plurality of reversible mobile bridge contacts respectively placed in the respective housings and each receiving the action of a pressure spring which applies them with an initial force against a cross piece separating two housings of a pair, these bridge contacts being adapted to cooperate each one with a pair of fixed reversible contacts disposed in the case, so as to form one or several possible configurations of opening or closing switches placed in signalling or power circuits.